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AJvYcCX3sY3P3dqN7Uxy/ZG/BrIk7yopubangBsupsY6PtN1s4GqtVILggt3ZyE6lP99ouB+BHyO4kUlHA==@kvack.org X-Gm-Message-State: AOJu0Yz+QBFRwlCkCmRJ9783MBuCbff1cRkmhBsdoNW5G4/l6tH7c8lx UrxUcDvRenvK4p6/n4amtExZXQaUmWP2BO1uDqq0iJWuPtpkn+YEKoTE+64BeVL2Jsun8OnPT6I 8sLcIcesioTnwiaZQa6oZADBsVA== X-Google-Smtp-Source: AGHT+IGm0uDnlmmvVqLxeQbS/GkNVcVJ1vJxluasBXbGw+YdYIXcsi2a/48HhtEUh6v1e/OBtWieEkqS8C8YBg1I5A== X-Received: from pjbpm17.prod.google.com ([2002:a17:90b:3c51:b0:33b:b692:47b0]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:4c4e:b0:32e:6019:5d19 with SMTP id 98e67ed59e1d1-33bcf921526mr5690604a91.34.1760731948481; Fri, 17 Oct 2025 13:12:28 -0700 (PDT) Date: Fri, 17 Oct 2025 13:11:41 -0700 Mime-Version: 1.0 X-Mailer: git-send-email 2.51.0.858.gf9c4a03a3a-goog Message-ID: Subject: [RFC PATCH v1 00/37] guest_memfd: In-place conversion support From: Ackerley Tng To: cgroups@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org Cc: ackerleytng@google.com, akpm@linux-foundation.org, binbin.wu@linux.intel.com, bp@alien8.de, brauner@kernel.org, chao.p.peng@intel.com, chenhuacai@kernel.org, corbet@lwn.net, dave.hansen@intel.com, dave.hansen@linux.intel.com, david@redhat.com, dmatlack@google.com, erdemaktas@google.com, fan.du@intel.com, fvdl@google.com, haibo1.xu@intel.com, hannes@cmpxchg.org, hch@infradead.org, hpa@zytor.com, hughd@google.com, ira.weiny@intel.com, isaku.yamahata@intel.com, jack@suse.cz, james.morse@arm.com, jarkko@kernel.org, jgg@ziepe.ca, jgowans@amazon.com, jhubbard@nvidia.com, jroedel@suse.de, jthoughton@google.com, jun.miao@intel.com, kai.huang@intel.com, keirf@google.com, kent.overstreet@linux.dev, liam.merwick@oracle.com, maciej.wieczor-retman@intel.com, mail@maciej.szmigiero.name, maobibo@loongson.cn, mathieu.desnoyers@efficios.com, maz@kernel.org, mhiramat@kernel.org, mhocko@kernel.org, mic@digikod.net, michael.roth@amd.com, mingo@redhat.com, mlevitsk@redhat.com, mpe@ellerman.id.au, muchun.song@linux.dev, nikunj@amd.com, nsaenz@amazon.es, oliver.upton@linux.dev, palmer@dabbelt.com, pankaj.gupta@amd.com, paul.walmsley@sifive.com, pbonzini@redhat.com, peterx@redhat.com, pgonda@google.com, prsampat@amd.com, pvorel@suse.cz, qperret@google.com, richard.weiyang@gmail.com, rick.p.edgecombe@intel.com, rientjes@google.com, rostedt@goodmis.org, roypat@amazon.co.uk, rppt@kernel.org, seanjc@google.com, shakeel.butt@linux.dev, shuah@kernel.org, steven.price@arm.com, steven.sistare@oracle.com, suzuki.poulose@arm.com, tabba@google.com, tglx@linutronix.de, thomas.lendacky@amd.com, vannapurve@google.com, vbabka@suse.cz, viro@zeniv.linux.org.uk, vkuznets@redhat.com, wei.w.wang@intel.com, will@kernel.org, willy@infradead.org, wyihan@google.com, xiaoyao.li@intel.com, yan.y.zhao@intel.com, yilun.xu@intel.com, yuzenghui@huawei.com, zhiquan1.li@intel.com Content-Type: text/plain; charset="UTF-8" X-Stat-Signature: 1xx74nuz5tugowwx43ox83g1xeo8e4ak X-Rspamd-Queue-Id: 232884000C X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1760731949-844797 X-HE-Meta: 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 Rip+yp8Q 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello, IIUC this is the first independent patch series for guest_memfd's in-place conversion series! Happy to finally bring this out on its own. Previous versions of this feature, part of other series, are available at [1][2][3]. Many prior discussions have led up to these main features of this series, and these are the main points I'd like feedback on. 1. Having private/shared status stored in a maple tree (Thanks Michael for your support of using maple trees over xarrays for performance! [4]). 2. Having a new guest_memfd ioctl (not a vm ioctl) that performs conversions. 3. Using ioctls/structs/input attribute similar to the existing vm ioctl KVM_SET_MEMORY_ATTRIBUTES to perform conversions. 4. Storing requested attributes directly in the maple tree. 5. Using a KVM module-wide param to toggle between setting memory attributes via vm and guest_memfd ioctls (making them mututally exclusive - a single loaded KVM module can only do one of the two.) 6. Skipping LRU in guest_memfd folios - make guest_memfd folios not participate in LRU to avoid LRU refcounts from interfering with conversions. This series is based on kvm/next, followed by + v12 of NUMA mempolicy support patches [5] + 3 cleanup patches from Sean [6][7][8] Everything is stitched together here for your convenience https://github.com/googleprodkernel/linux-cc/commits/guest_memfd-inplace-conversion-v1 Thank you all for helping with this series! If I missed out your comment from a previous series, it's not intentional! Please do raise it again. TODOs: + There might be an issue with memory failure handling because when guest_memfd folios stop participating in LRU. From a preliminary analysis, HWPoisonHandlable() is only true if PageLRU() is true. This needs further investigation. [1] https://lore.kernel.org/all/bd163de3118b626d1005aa88e71ef2fb72f0be0f.1726009989.git.ackerleytng@google.com/ [2] https://lore.kernel.org/all/20250117163001.2326672-6-tabba@google.com/ [3] https://lore.kernel.org/all/b784326e9ccae6a08388f1bf39db70a2204bdc51.1747264138.git.ackerleytng@google.com/ [4] https://lore.kernel.org/all/20250529054227.hh2f4jmyqf6igd3i@amd.com/ [5] https://lore.kernel.org/all/20251007221420.344669-1-seanjc@google.com/T/ [6] https://lore.kernel.org/all/20250924174255.2141847-1-seanjc@google.com/ [7] https://lore.kernel.org/all/20251007224515.374516-1-seanjc@google.com/ [8] https://lore.kernel.org/all/20251007223625.369939-1-seanjc@google.com/ Ackerley Tng (19): KVM: guest_memfd: Update kvm_gmem_populate() to use gmem attributes KVM: Introduce KVM_SET_MEMORY_ATTRIBUTES2 KVM: guest_memfd: Don't set FGP_ACCESSED when getting folios KVM: guest_memfd: Skip LRU for guest_memfd folios KVM: guest_memfd: Add support for KVM_SET_MEMORY_ATTRIBUTES KVM: selftests: Update framework to use KVM_SET_MEMORY_ATTRIBUTES2 KVM: selftests: guest_memfd: Test basic single-page conversion flow KVM: selftests: guest_memfd: Test conversion flow when INIT_SHARED KVM: selftests: guest_memfd: Test indexing in guest_memfd KVM: selftests: guest_memfd: Test conversion before allocation KVM: selftests: guest_memfd: Convert with allocated folios in different layouts KVM: selftests: guest_memfd: Test precision of conversion KVM: selftests: guest_memfd: Test that truncation does not change shared/private status KVM: selftests: guest_memfd: Test conversion with elevated page refcount KVM: selftests: Reset shared memory after hole-punching KVM: selftests: Provide function to look up guest_memfd details from gpa KVM: selftests: Make TEST_EXPECT_SIGBUS thread-safe KVM: selftests: Update private_mem_conversions_test to mmap() guest_memfd KVM: selftests: Add script to exercise private_mem_conversions_test Sean Christopherson (18): KVM: guest_memfd: Introduce per-gmem attributes, use to guard user mappings KVM: Rename KVM_GENERIC_MEMORY_ATTRIBUTES to KVM_VM_MEMORY_ATTRIBUTES KVM: Enumerate support for PRIVATE memory iff kvm_arch_has_private_mem is defined KVM: Stub in ability to disable per-VM memory attribute tracking KVM: guest_memfd: Wire up kvm_get_memory_attributes() to per-gmem attributes KVM: guest_memfd: Enable INIT_SHARED on guest_memfd for x86 Coco VMs KVM: Move KVM_VM_MEMORY_ATTRIBUTES config definition to x86 KVM: Let userspace disable per-VM mem attributes, enable per-gmem attributes KVM: selftests: Create gmem fd before "regular" fd when adding memslot KVM: selftests: Rename guest_memfd{,_offset} to gmem_{fd,offset} KVM: selftests: Add support for mmap() on guest_memfd in core library KVM: selftests: Add helpers for calling ioctls on guest_memfd KVM: selftests: guest_memfd: Test that shared/private status is consistent across processes KVM: selftests: Add selftests global for guest memory attributes capability KVM: selftests: Provide common function to set memory attributes KVM: selftests: Check fd/flags provided to mmap() when setting up memslot KVM: selftests: Update pre-fault test to work with per-guest_memfd attributes KVM: selftests: Update private memory exits test work with per-gmem attributes Documentation/virt/kvm/api.rst | 72 ++- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/Kconfig | 15 +- arch/x86/kvm/mmu/mmu.c | 4 +- arch/x86/kvm/x86.c | 13 +- include/linux/kvm_host.h | 44 +- include/trace/events/kvm.h | 4 +- include/uapi/linux/kvm.h | 17 + mm/filemap.c | 1 + mm/memcontrol.c | 2 + tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile.kvm | 1 + .../kvm/guest_memfd_conversions_test.c | 498 ++++++++++++++++++ .../testing/selftests/kvm/include/kvm_util.h | 127 ++++- .../testing/selftests/kvm/include/test_util.h | 29 +- tools/testing/selftests/kvm/lib/kvm_util.c | 128 +++-- tools/testing/selftests/kvm/lib/test_util.c | 7 - .../selftests/kvm/pre_fault_memory_test.c | 2 +- .../kvm/x86/private_mem_conversions_test.c | 55 +- .../kvm/x86/private_mem_conversions_test.py | 159 ++++++ .../kvm/x86/private_mem_kvm_exits_test.c | 36 +- virt/kvm/Kconfig | 4 +- virt/kvm/guest_memfd.c | 414 +++++++++++++-- virt/kvm/kvm_main.c | 104 +++- 24 files changed, 1554 insertions(+), 185 deletions(-) create mode 100644 tools/testing/selftests/kvm/guest_memfd_conversions_test.c create mode 100755 tools/testing/selftests/kvm/x86/private_mem_conversions_test.py -- 2.51.0.858.gf9c4a03a3a-goog